Rename the visible VoxIP texts to Daynivo

Product name (Daynivo Kiosk OS), default device name, kiosk screens,
service descriptions, installer output and docs. Internal names
(voxip-kiosk-*, /etc/voxip-kiosk, user voxip, VOXIP_* variables) stay.
An update renames a device still called "VoxIP Kiosk" to the new default.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

www/setup.html

@@ -2,7 +2,7 @@
 <html lang="nl">
 <head>
   <meta charset="utf-8">
-  <title>VoxIP Kiosk — eerste configuratie</title>
+  <title>Daynivo Kiosk — eerste configuratie</title>
   <link rel="stylesheet" href="kiosk.css">
 </head>
 <body>
@@ -26,7 +26,7 @@
     </main>
     <footer class="bottom">
       <span></span>
-      <span>VoxIP Kiosk</span>
+      <span>Daynivo Kiosk</span>
     </footer>
   </div>
   <script src="kiosk.js"></script>